This invention relates generally to cargo handling and more particularly to recovering dry residual, particulate bulk materials from the holds of ships and the cleaning of these holds.
The need to clean residual bulk particulate cargoes, like cement, petroleum coke (carbon), ash, ores, bauxite, coal, from the holds of ships has been present as long as vessels have been carrying such cargoes; yet an efficient, economical, and environmentally friendly means to accomplish this end, and still recover residual cargoes, has heretofore not been developed. Ships' holds are, to this day, still cleaned by primitive methods, with shovels, scrapers and brooms. On ships without cargo gear, residues of cargoes are hoisted by hand up to the deck in drums. Truck mounted vacuum cleaning systems are widely utilized in shore-based industry, but are considered impractical for ship cleaning for three main reasons. Ships often discharge at an anchorage or at a floating terminal, which are, obviously, inaccessible to trucks. At many docks, truck access is impossible due to the presence of discharge equipment or to obstructions such as pipelines. Finally, some dock facilities are on barges or floats, or are located on piers out in the water, with no truck access.
With the exception of high-pressure water blasting equipment for removal of scale and hardened residues of previous cargoes, which is not a subject of this disclosure, the "technology" of ship hold cleaning has not changed in many years. Ships lose days of valuable time lying idle while cleaning gangs work. A typical Panamax vessel (60,000 deadweight tons) takes a week to clean after discharging a bulk cement cargo. The residue of cargo cleaned is either dumped in a landfill or sold at a reduced price as secondary material.
After discharging the cargo and sweeping out the holds, the final part of the cleaning process consists of washing down the holds. With some dirty cargoes, particularly bulk cement, the ship must then transit out to sea to pump dirty cargo/water slurry over the side, incurring, in some cases, tens of thousands of dollars in expenses to return to the same port. Unscrupulous owners have the dirty water pumped over the side into the port or river. Having water pumps and filters available to purify the dirty water from an in-port washdown would be a great benefit, if the ship were to load her next cargo from the same port. In years past, pumping the dirty water overboard was common practice. It is now forbidden due to environmental restrictions. It is desirable to be able to clean this wash water to permit the ship to load in the same port where it just discharged and to eliminate pollution when this water is discharged.
There are no boat or barge mounted systems in use or in the literature which perform this function. While the disclosure in U.S. Pat. No. 4,016,994 briefly suggests, in passing, that the truck mounted cleaning system could be installed on a boat, it contemplates that this installation would be for the purpose of cleaning oil spills, not the recovery of cargoes and cleaning of hulls. Most significantly, the '994 patent provides nothing other than the bare suggestion of the use of a vessel and, of course, the truck operated system of the patent does not disclose the features of the subject invention.
In the past, ship costs were small and the time for cleaning inconsequential; labor was cheap and readily available, and environmental restrictions were lax or non-existent. With the advent of large ships with long delays in cleaning, progressively higher wage rates, and severe environmental laws and regulations, a vessel recovery system which efficiently and economically recovers residual cargo from holds, while providing environmentally safe cleaning capabilities would be of great benefit to the cargo handling industry.
Accordingly, it is the object of the present invention to provide a self-contained ship's cargo recovery and cleaning vessel which overcomes the limitations and deficiencies of prior vessels.
It is the object of the present invention to provide a self-contained ship's cargo recovery and cleaning vessel which effectively recovers residual particulate cargo from the holds of ships.
It is another object of the present invention to provide a self-contained ship's cargo recovery and cleaning vessel which effectively collects and accumulates residual particulate cargo for delivery to designated cargo receptacles.
It is a further object of the present invention to provide a self-contained ship's cargo recovery and cleaning vessel which effectively and efficiently cleans trace residual particulate cargo from ship holds.
It is still another object of the present invention to provide a self-contained ship's cargo recovery and cleaning vessel which recovers and cleans residual particulate cargo from ship holds by using a system of vacuum exhausters and collectors which can be used on the vessel or are separable from the vessel for use off the vessel.
It is another object of the present invention to provide a self-contained ship's cargo recovery and cleaning vessel which has the capability of washing the holds of ships with water, filtering the water, with the resultant clean water discharged or stored as ballast.
It is still another object of the present invention to provide a self-contained ship's cargo recovery and cleaning vessel which allows a bulk particulate cargo ship to discharge its cargo and then load in the same port, without losing cargo or risking pollution from hold cleaning.
It is a further object of the present invention to provide a self-contained ship's cargo recovery and cleaning vessel which permits flexible off loading of residual particular cargoes and cleaning of ship holds at discharge sites which are inaccessible to land based vehicles.
It is an additional object of the present invention to provide a self-contained ship's cargo recovery and cleaning vessel which provides a recovery and ship's hold cleaning system which is fast and economical, allowing the recovery of substantially all cargo, thus increasing the value of the cargo shipment.
The present invention comprises a self-contained floating vessel which may be self-propelled or barge-like in configuration. It is equipped with a vacuum exhaust unit configured to pull an air-stream vacuum, by means of pipe and hose lines, from ship cargo holds which contain residual particulate cargo. Primary and secondary collectors are used to separate the particulate cargo from the air-stream. The air-stream with particulate cargo is separated in the first collector by a series of baffles. Approximately ninety-five percent of the residual cargo drops to the bottom of and accumulates within the primary collector, where it is recovered through a dump valve in the collector. The remaining air-stream/particulate cargo mixture is pulled through the secondary collector, which filters and recovers the particulate from the air-stream by means of filters. The cargo particulate is also accumulated in the secondary collector, where it is recovered through a dump valve. The collectors can function within the hull of the self-contained vessel or can be separated from the hull and transported by floating crane or alternate ship or shoreside lifting devices and placed on recovery receptacles, such as cargo bays, cargo barges or positioned over jumbo cargo bays.
After the cargo is removed, the vessel cargo holds are washed down to remove traces of cargo, so as to permit loading of new cargo. The waste water is pumped through filters to remove the trace cargo. The filtered water can then be pumped into the ship's ballast tanks or, depending on the cargo, pumped directly overboard.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention, itself, both as to its design, construction, and use, together with additional features and advantages thereof, are best understood upon review of the following detailed description with reference to the accompanying drawings.